It is when one Republican, U.S. Rep. Justin Amash, surprises the other, primary challenger Brian Ellis, by calling into a live radio talk show to defend his record. The verbal sparring was just one more highlight in a campaign in which the candidates are calling each other RINOs, and believing they are battling for not only a U.S. House seat but also the soul of the Republican Party.

Amash and Ellis are locked in an epic GOP congressional primary race in Michigan’s conservative 3rd Congressional District, where a Democrat hasn’t won the presidential election since the LBJ landslide buried Barry Goldwater in 1964.

Brian Ellis, the president of Grand Rapids-based Brooktree Capital Management, whose only political experience is his 15 years on the suburban East Grand Rapids school board, entered the primary in August 2014 because he believes Amash — a Tea Party favorite — is not conservative enough.

“Amash talks the game, but doesn’t vote the game,” Ellis said.

Amash, a 33-year-old attorney, was the second-youngest member of the U.S. House when he won the November 2010 election. The second-generation Arab-American served in the Michigan House of Representatives before he won his first GOP primary in 2010. Amash defeated Patrick Miles — a Democrat who was a Harvard University classmate of President Barack Obama — the following November.

Amash campaigned as a “principled conservative” and has described himself as a Libertarian, sending birthday cards to former Rep. Ron Paul (R-Texas) who reciprocated with a two-day fundraiser that pulled in $100,000 for Amash.

After easily winning reelection in 2012, Amash, along with Rep. Tim Huelskamp (R-Kansas), tried to unseat House Speaker John Boehner (R-Ohio).

The coup failed. Amash was kicked off the House Budget Committee, something he described on his Facebook page as “a slap in the face.”

It must have felt like a punch in the gut when not one single Michigan Republican in Congress donated even one thin dime to the Amash campaign in the first quarter of 2014.

The Detroit News reported at least two retiring congressmen gave money to Ellis, though, and House Intelligence Committee Chairman Mike Rogers (R-Mich.) came close to endorsing Ellis.

Hardly surprising if only because of the failed coup attempt, but House leadership isn’t backing Amash either.

However, Boehner isn’t the only Republican who has had it with Amash. Karl Rove has called him the “most liberal Republican” in Congress. National Journal branded Amash the fifth most liberal Republican in Congress in 2013, and said he was the Republican who voted least often with his party.

Ellis’ main campaign theme is Amash is not conservative enough and has a record of “bizarre” votes.

“If you have somebody that doesn’t vote for a balanced budget amendment, didn’t support the Keystone pipeline, didn’t vote for a small-business tax cut, didn’t support the pro-life agenda on critical votes, who’s the RINO?” said Ellis.